1. Field of the Invention
This invention relates generally to the field drywall construction and more particularly to a drywall corner bead that can be finished on both sides wet with a standard mud dispensing box typical in the trade.
2. Description of the Related Art
For years in the drywall trade, automatic taping tool companies have tried to come up with a tool to box corners in one step. Boxing a corner means putting drywall mud on both sides of it in a condition that can later be sanded and painted. The problem with boxing traditional corners is that only one side at a time can be tooled. If an attempt is made to tool both sides of a corner at the same time, either the guide on the mud dispensing box will disturb (and ruin) the mud on the other side of the corner, or the mud coming out of the box will flow onto the other side. In either case, the corner would be left in an unacceptable condition. This has forced tooling or boxing only one side of each corner at a time. One side is tooled, then the mud must be allowed to dry, a process that requires coming back at least a day later. Only after the mud on the first side is totally dry, can the second side be tooled. Workers must typically pass through a construction site tooling only first sides of corners. They must then come back on a subsequent day to tool the second sides. This puts at least an extra day into the construction cycle.
What is badly needed it a corner bead that will allow a standard mud dispensing box to tool both sides of a corner while the mud is still wet. This corner should be available in standard or bullnose (rounded) styles for exterior corners, and should be a available as a flex-trim for interior corners. The worker should be able to mud one side and immediately mud the other.
The present invention relates to a drywall corner bead that can be mudded on both sides while the mud is still wet. At the apex of the bead, there is a flat finished surface that is prepared to receive paint or texture. This apex is shaped so that a standard mud dispensing box can deposit mud down one side without the mud running up entirely to the apex. Thus a finished side can be mudded without any mud on the apex. This then allows the box to mud the second side without any interference to the first side.
The bead resembles a standard corner bead with two flanges. The flanges can be flat or can taper or be beveled. The flanges can be nailed, glued, or mudded onto the wallboard. At the apex is the finished surface that never needs mud. The surface of the apex can be finished in any way that will allow it to take paint or texture. It can be roughed slightly, or it can be coated by a material to which paint or texture will adhere. The bead can be made from any plastic, high impact plastic, metal, or any other rigid material.
In the process, the worker cuts the bead to length and attaches it to the corner by any method (nailing, gluing, or mudding), and then muds the first side with a standard box. At typical box is seven inches. Immediately after mud is applied to the first side, the worker can move to the second side and mud it in an identical manner. The corner is thus totally mudded in minutes without any drying wait period. The boxable bead can be supplied in regular or bullnose styles for exterior corners, and interior trim or flex-trim for interior corners. It can come in standard lengths, or for trim, optionally in rolls.
The shape of the apex or nose on both the exterior and interior beads is the key to the ability of the present invention to function and totally distinguishes the present invention from the prior art. This unique shape allows the mud box to dispense mud on one side without the mud slopping over to the other side. This shape also allows a special two-part mud box to be designed that can dispense mud on both sides simultaneously.
Prior art corner beads with any shape of nose would allow mud to slop over when being applied to one side. In all prior art systems, mud must be applied to one side and then allowed to dry before new wet mud can be applied to the other side.
The special shape feature of all the apexes of the present invention is a wide flat area coming off the tip followed by a quick drop-off into the region designed to be mudded on each side. This flat area appears on a pointed apex for a sharp corner, a bullnose apex for a rounded corner or a sharp interior corner. Other shapes simply will not work.
On the exterior trim piece, an elongated protruding nose member is attached to a pair of flanges along the centerline on the room facing side. The protruding nose member has an elongated tip running parallel to the centerline end-to-end. The tip is formed by a pair of flat surfaces meeting at an angle where each of the surfaces is approximately parallel to one of the flanges respectively. The flat surfaces extend away from the elongated tip a predetermined distance to a taper point where they end, and the nose member quickly tapers into the flanges beyond the taper point. This way the elongated protruding nose member prevents wet mud applied to one of the flanges from crossing over to the other of the flanges. The actual tip can be pointed for a square corner or rounded (arcuate) for a bullnose corner.
On the interior trim piece, the flanges are initially laid out flat (unfolded). An elongated trapezoidal nose member is attached to the flanges along the centerline on the room facing side and runs parallel to the centerline. The nose member has a flat top also parallel to the flanges which extends away from the centerline for a predetermined distance to a taper point. Beyond the taper point, the flat top ends, and the nose member quickly tapers into the flanges. An elongated groove runs end-to-end along the centerline on the wall facing side of the flanges. The groove penetrates into the nose member forming a hinge that allows the flanges and the nose member to bend along the hinge to form an acute angle on the room facing side. The flat top on the nose member now forms two sections (after folding to match the wall angle), each section is still approximately parallel to one of the flanges. The sections form an acute angle on the room facing side such that the two sections on the nose member prevent wet mud applied to one of the flanges from crossing over to the other of the flanges.